Thermal printers are widely known and generally comprises a printing means comprising a thermally activatable printhead for printing onto an image receiving tape. Typically, the image receiving tape has an upper layer for receiving an image and a removable liner layer or backing layer secured to the upper layer by a layer of adhesive, such that after an image has been printed the liner layer or backing layer can be removed and the image receiving tape can be stuck down in the form of a label. Such thermal printers include cutters for cutting off a length of image receiving tape after the image has been printed. Such thermal printers operate with a consumable in the form of image receiving tape, or any other image receiving substrate such as heat-shrink tubes, magnetic, iron-on labels, plastic strips, etc.
In addition, the printer can utilise an ink ribbon cassette which supplies ink ribbon in overlap with the image receiving tape at the printhead.
The term “consumable” is used herein to denote any appropriate form of providing image receiving tape or image transferring substance. A number of forms of consumables are known in the art, including cassettes which comprise a housing in which is located a supply of image receiving tape. Cassettes are generally usable once only, such that once the image receiving tape has been consumed, the cassette (including the housing) is thrown away.
Another type of consumable is a holder, which comprises a spool around which image receiving tape is wound. The spool may or may not be driven, and generally comprises a plastic component.
Another type of consumable is a roll of tape without a permanent holder, for example wound on a paper core. These are termed “supplies”.
As already mentioned, in thermal printers, an image is generally generated by activation of a thermal printhead against an ink ribbon cassette, such that ink from the ink ribbon is transferred onto the image receiving tape at a print zone. So-called direct thermal tapes are also available, in which an image is created directly onto the direct thermal tape without the interposition of an ink ribbon cassette. The term “consumable” also encompasses ink ribbon or other thermal transfer materials.
It is known in the art to provide a consumable, mostly a cassette, which has means for identifying parameters of the image receiving tape inside the cassette. For example, the cassette may identify the width of the image receiving tape, the nature of the image receiving tape (for example its material properties, thermal transfer, direct thermal etc.) or other tape parameters. It is also known to use these parameters in controlling certain operations of printing apparatus. For example, the width of the tape can be detected and the size of characters to be printed can be adjusted accordingly.
A piece of information which is particularly interesting is the amount of tape which is remaining which can be used for printing each time a consumable is inserted into a thermal printing apparatus. It is an aim of the present invention to allow such information to be held at a consumable in a convenient and secure manner.
Reference is made to U.S. Pat. No. 5,821,975 (Francotyp-Postalia AG & Co.) which relates to a franking machine. In particular, that patent discloses that an ink ribbon cassette can have a memory (optical, magnetic or electronic) which holds information relating to the degree of usage of the ink ribbon. Reference is also made to WO98/05508 which uses an RF tag in the context of adapting a transfer ribbon and a receiver material. Nothing in these documents relates to the problem of updating status information associated with an image receiving tape.
Reference is also made to EP-A-1066969 (Brady Worldwide, Inc.) which describes a system where the consumable comprises a plurality of pre-cut labels secured by adhesive to a label web. An inventory of labels is read from a memory device associated with the labelling medium supply spool. After each label is printed, the inventory of labels is altered by writing data to the memory device. Therefore, the inventory of labels indicates how many labels have been used, and therefore how many labels are remaining assuming that the initial number of labels on the web is known. This requires a memory chip associated with the labelling medium.
Reference is also made to U.S. Pat. No. 5,605,404 (Seiko Epson). This document discloses a tape cartridge cooperable with a thermal printer, the tape cartridge having a one chip microprocessor which holds information about the tape in the tape cartridge. In particular, the microprocessor can hold information including a residual amount of tape in the tape cartridge, a code representing a user, a consumed amount of tape and/or a password. The microprocessor can be updated to indicate the amount of tape left in the tape cartridge by determining the used tape length by counting the number of steps of the stepping motor.
This device however requires the use of a microprocessor at the tape cartridge, which increases the cost of the tape cartridge. Moreover, electrical connections are required for the microprocessor.